Protecting groups in polymers, photoresists and processes for microlithography

ABSTRACT

The invention relates to a photoresist composition having a protecting group and a protected material incorporated in a cyclic chemical structure. In this invention a protected material has a cyclic ether group or cyclic ester group as a protecting group. A specific example of a cyclic ether group is an alkylene oxide, such as an oxetane group, substituted with one or more fluorinated alkyl groups. A specific example of a cyclic ester is a lactone which may be substituted with methyl groups. The photoresist composition further includes a photoactive component. The photoresist composition of this invention has a high transparency to ultraviolet radiation, particularly at short wavelengths such as (193) nm and (157) nm.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention pertains to photoimaging and, inparticular, the use of photoresists (positive-working and/ornegative-working) for imaging in the production of semiconductordevices. The present invention also pertains to novelfluorine-containing polymer compositions having high UV transparency(particularly at short wavelengths, e.g., 157 nm) which are useful asbase resins in photoresist and potentially in many other applications.

[0003] 2. Description of Related Art

[0004] Polymer products are used as components of imaging andphotosensitive systems and particularly in photoimaging systems such asthose described in Introduction to Microlithography, Second Edition byL. F. Thompson, C. G. Willson, and M. J. Bowden, American ChemicalSociety, Washington, DC, 1994. In such systems, ultraviolet (UV) lightor other electromagnetic radiation impinges on a material containing aphotoactive component to induce a physical or chemical change in thatmaterial. A useful or latent image is thereby produced which can be,processed into a useful image for semiconductor device fabrication.

[0005] Although the polymer product itself may be photoactive, generallya photosensitive composition contains one or more photoactive componentsin addition to the polymer product. Upon exposure to electromagneticradiation (e.g., UV light), the photoactive component acts to change theTheological state, solubility, surface characteristics, refractiveindex, color, electromagnetic characteristics or other such physical orchemical characteristics of the photosensitive composition as describedin the Thompson et al. publication supra.

[0006] For imaging very fine features at the submicron level insemiconductor devices, electromagnetic radiation in the far or extremeultraviolet (UV) is needed. Positive working resists generally areutilized for semiconductor manufacture. Lithography in the UV at 365 nm(I-line) using novolak polymers and diazonaphthoquinones as dissolutioninhibitors is a currently established technology having a resolutionlimit of about 0.35-0.30 micron. Lithography in the far UV at 248 nmusing p-hydroxystyrene polymers is known and has a resolution limit of0.35-0.18 nm. There is strong impetus for future photolithography ateven shorter wavelengths, due to a decreasing lower resolution limitwith decreasing wavelength (i.e., a resolution limit of 0.18-0.12 micronfor 193 nm imaging and a resolution limit of about 0.07 micron for 157nm imaging). Photolithography using 193 nm exposure wavelength (obtainedfrom an argon fluorine (ArF) excimer laser) is a leading candidate forfuture microelectronics fabrication using 0.18 and 0.13 μm design rules.Photolithography using 157 nm exposure wavelength (obtained from afluorine excimer laser) is a leading candidate for futuremicrolithography further out on the time horizon (beyond 193 nm)provided suitable materials can be found having sufficient transparencyand other required properties at this very short wavelength. The opacityof traditional near UV and far UV organic photoresists at 193 nm orshorter wavelengths precludes their use in single-layer schemes at theseshort wavelengths.

[0007] Development of photoresist compositions having one or moreprotected acidic groups may be by catalysis of acids or bases generatedphotolytically from photoactive compounds (PACs) which yield hydrophilicacid groups. A given protected acid group is one that is normally chosenon the basis of its being acid labile, such that when photoacid isproduced upon imagewise exposure, the acid will catalyze deprotectionand production of hydrophilic acid groups for development under aqueousconditions.

[0008] Examples of components having protected acidic groups that yieldan acidic group as the hydrophilic group upon exposure to photogeneratedacid include, but are not limited to, A) esters capable of forming, orrearranging to, a tertiary cation, B) esters of lactone, C) acetalesters, D) β-cyclic ketone esters, E) α-cyclic ether esters, F) MEEMA(methoxy ethoxy ethyl methacrylate) and other esters which are easilyhydrolyzable because of anchimeric assistance, G) carbonates formed froma fluorinated alcohol and a tertiary aliphatic alcohol. Some specificexamples in category A) are t-butyl ester, 2-methyl-2-adamantyl ester,and isobornyl ester. Some specific examples in category B) areγ-butyrolactone-3-yl, γ-butyrolactone-2-yl, mavalonic lactone,3-methyl-γ-butyrolactone-3-yl, 3-tetrahydrofuranyl, and 3-oxocyclohexyl.Some specific examples in category C) are 2-tetrahydropyranyl,2-tetrahydrofuranyl, and 2,3-propylenecarbonate-1-yl. Additionalexamples in category C) include various esters from addition of vinylethers, such as, for example, ethoxy ethyl vinyl ether, methoxy ethoxyethyl vinyl ether, and acetoxy ethoxy ethyl vinyl ether.

[0009] It has been found that these protecting groups may generatevolatile products during exposure because of deprotection before anypost-exposure heating step, especially as exposure wavelengths aredecreased for new imaging systems. Production of volatile products onexposure is disadvantageous since such volatiles can coat exposuredevice lenses and negatively affect their imaging properties, requiringexpensive cleaning processes. Loss of volatile material can also causeshrinkage in the imaged areas of the photoresists and negatively affectimage quality.

[0010] JP 11012326 publication discloses the following reaction:

[0011] This suggests that the lactone ring can be opened by photoacidcatalysis, but also clearly indicates that this reaction requires thepresence of moisture, and that the reaction is terminated in the absenceof moisture. In this process water as an external agent is used forreaction. Processes not requiring an external agent, in addition to aphotoacid generator, would be advantageous.

[0012] There is a need for protecting groups for polymer resistcompositions, for use particularly at 193 nm or 157 nm, that providedeprotection without the generation of volatiles.

SUMMARY OF THE INVENTION

[0013] Volatile components are those materials that will evaporate outof the polymeric ingredients of the photoresist composition causingcoating of exposure lenses, and a loss of polymer mass that may lead topoor image quality. The invention is related to incorporating aprotecting group and a polar group (that is to be protected) in a cyclicstructure so that volatile components are not released duringdeprotection of the polar group by photogenerated catalyst leading tosolubility in developer. This approach can be used for both thepolymeric binder of the photoresist composition and/or the dissolutioninhibitor of the photoresist composition.

[0014] In a first aspect, the invention provides a photoresistcomposition comprising:

[0015] (a) a protected material comprising:

[0016] A. one or more cyclic ether groups having structure I or II:

[0017] wherein R_(f) and R_(f)′ independently represent fluoroalkylgroups of from one to about ten carbon atoms or taken together are(CF₂)_(a) wherein a is an integer ranging from 2 to about 10, Rindependently represents a hydrogen atom or a straight chain or branchedchain alkyl group of 1 to about 10 carbon atoms, and p is an integer offrom 0 to about 8; wherein the protected material is substantially freeof an acid group with a pKa of <11; and

[0018] (Y) one or more cyclic esters having structure III:

[0019] wherein R₁ and R₂ independently represent an unsubstitutedstraight chain or branched chain alkyl group having 1 to 10 carbonatoms; aromatic, aralkyl, or alkaryl group having 6 to 14 carbon atoms;or substituted groups thereof containing at least one O, S, N, P orhalogen; and n is an integer ranging from 1 to about 4; and

[0020] (b) a photoactive component.

[0021] In a second aspect, the invention relates to a process forpreparing a photoresist image on a substrate comprising, in order:

[0022] (W) providing a photoresist layer on a substrate, wherein thephotoresist layer is prepared from a photoresist composition comprising:

[0023] (a) a protected material comprising a group which is:

[0024] A. one or more cyclic ether groups having structure I or II;

[0025] wherein R_(f) and R_(f)′ independently represent fluoroalkylgroups of from one to about ten carbon atoms or taken together are(CF₂)_(a) wherein a is an integer ranging from 2 to about 10, Rindependently represents a hydrogen atom or a straight chain or branchedchain alkyl group of 1 to about 10 carbon atoms, and p is an integer offrom 0 to about 8; wherein the protected material is substantially freeof an acid group with a pKa of <11; and

[0026] B. one or more cyclic esters having structure III:

[0027] wherein R₁ and R₂ independently represent an unsubstitutedstraight chain or branched chain alkyl group having 1 to 10 carbonatoms; aromatic, aralkyl, or alkaryl group having 6 to 14 carbon atoms;or substituted groups thereof containing at least one O, S, N, P orhalogen; n is an integer ranging from 1 to about 4; and

[0028] (b) a photoactive component;

[0029] (X) imagewise exposing the photoresist layer to form imaged andnon-imaged areas; and

[0030] (Y) developing the exposed photoresist layer having imaged andnon-imaged areas to form the relief image on the substrate.

[0031] An example of a cyclic ether group represented by (A) is anoxetane group having the following structure:

[0032] An example of a cyclic ester group represented by (B) is providedby a substituted lactone having the following structure:

[0033] A polymer containing this group can be obtained by incorporatingthe dimethyl tulipalin monomer(γ,γ-dimethyl-α-methylene-γ-butyrolactone). The deprotection of thesetwo classes of protecting groups is catalyzed by photogenerated acidwithout the requirement that moisture be present and without thegeneration of volatiles.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) Protecting Groups

[0034] The protected material comprises a protecting group selected fromthe group consisting of one or more cyclic ether groups or cyclic estergroups having the structures A or B, as shown above.

[0035] Materials containing a cyclic ether group represented bystructure I may be prepared, for example, by hypochlorite oxidation ofcompounds containing the —CH═CR_(f)R_(f)′ fragment as described in WO2000/066575A2. Materials containing the cyclic ether protecting grouprepresented by structure 11 wherein p is 0 may be prepared, for example,by the method disclosed in U.S. Pat. No. 3,164,610 (1964) or in Izv.Akad. Nauk. Ser. Khim. 1967, pp. 918-921 using the reaction ofcorresponding vinyl ether with hexafluoroacetone. Materials containingthe cyclic ether group wherein p is 0 to about 8 may be prepared bycyclization of α-haloethers of structure—O—CHCl—CHR—(CRR)_(p)—C(R_(f)R_(f)′)OH in the presence of base.

[0036] Cyclic ether groups of formula I or II may be converted thermallyor by action of catalytic amount of acid into a fluoroalcohol containingmaterial of formulas I′ and II′, respectively, as a result ofring-opening processes presented below:

[0037] The cyclic esters which can be converted into a carboxylic acidmay be substituted lactones Which open in the presence of strong acid.An example is the polymerizable monomer, dimethyl tulipalin(γ,γ-dimethyl-α-methylene-γ-butyrolactone. Such functional groups canalso be attached to non-polymeric structures.

[0038] The point of attachment of the protected material to theprotecting group in structure I or II will be to a carbon atom which isa substituent of the ether ring. At least one point of attachment of theprotected material to the protecting group in structure III will bethrough a saturated ring carbon of the structure or R₁ or R₂.

Protected Material

[0039] The protected material may be a binder or a dissolutioninhibitor.

[0040] The binder may be a polymeric binder. Examples include allpolymers useful as photoresists such as those of the type disclosed inWO 00/17712 published Mar. 20, 2000, WO 00/25178 published May 4, 2000,and PCT/US00/11539 filed Apr. 28, 2000, with the proviso that thephotoresist composition in its unexposed state does not have acid groupswith a pKa of <11, typically <12, and more typically <14 when theprotecting group is a cyclic ether represented by Structures I and II.

[0041] The polymer binder may be a fluorine-containing polymer. Thefluorine-containing polymer may further comprise a repeat unit derivedfrom at least one ethylenically unsaturated compound containing afunctional group having the structure:

—C(R_(f))(R_(f)′)OR₃

[0042] wherein R_(f) and R_(f)′ are the same or different fluoroalkylgroups of from 1 to about 10 carbon atoms or taken together are(CF₂)_(n) wherein n is 2 to about 10, and R₃ is a hydrogen atom or anacid labile protecting group, when the protected material is a cyclicether group R₃ is an acid labile protecting group.

[0043] The fluoroalkyl groups designated as R_(f) and R_(f)′, can bepartially fluorinated alkyl groups or fully fluorinated alkyl groups(i.e., pertluoroalkyl groups).

[0044] Broadly, R_(f) and R_(f)′ are each independently represented byfluoroalkyl groups of from 1 to about 10 carbon atoms or taken togetherare (CF₂)_(n) wherein n is an integer ranging from 2 to about 10. Theterms “taken together” mean that R_(f) and R_(f)′ are not separate,discrete fluorinated alkyl groups, but that together they form a ringstructure of 3 to about 11 carbon atoms such as is illustrated below incase of 5-membered rings:

[0045] When R_(f) and R_(f)′ are partially fluorinated alkyl groupsthere must be a sufficient degree of fluorination present to impartacidity to the hydroxyl (—OH) of the ring opened form, such that thehydroxyl proton is substantially removed in basic media, such as inaqueous sodium hydroxide solution or tetraalkylammonium hydroxidesolution. Typically, there will be sufficient fluorine substitutionpresent in the fluorinated alkyl groups of the fluoroalcohol functionalgroup in the ring opened form such that the hydroxyl group will have apKa value as follows: 5<pKa<11.

[0046] Preferably, R_(f) and R_(f)′ are independently perfluoroalkylgroup of 1 to about 5 carbon atoms, and, most preferably, R_(f) andR_(f)′ are both trifluoromethyl (CF₃). A protected material containingthe protecting group of structure II when p is 0 or 1 and R is ahydrogen atom are preferred.

[0047] When the protected material is a polymeric binder, it may also beprepared from ethylenically unsaturated monomers by free radicalpolymerization or metal-catalyzed vinyl addition polymerizationprocesses known in the art to afford a polymer having a repeat unit thatis derived from the ethylenically unsaturated monomer. Specifically, anethylenically unsaturated compound having structure:

[0048] that undergoes free radical polymerization will afford a polymerhaving a repeat unit:

[0049] where P, Q, S, and T independently can be the same or differentand illustratively could be fluorine, hydrogen, chlorine, andtrifluoromethyl.

[0050] If only one ethylenically unsaturated compound undergoespolymerization, the resulting polymer is a homopolymer. If two or moredistinct ethylenically unsaturated compounds undergo polymerization, theresulting polymer is a copolymer.

[0051] Some representative examples of ethylenically unsaturatedcompounds and their corresponding repeat units are described below:

[0052] For metal catalyzed vinyl addition polymerization a usefulcatalyst is a nickel containing complex. Neutral Ni catalysts aredescribed in WO 9830609. Other references regarding thesalicylaldimine-based neutral nickel catalysts include WO PatentApplication 9842664. Wang, C..; Friedrich, S.; Younkin, T. R.; Li, R.T.; Grubbs, R. H.; Bansleben, D. A.; Day, M. W. Organometallics 1998,17(15), 314 and Younkin, T.; Connor, E. G.; Henderson, J. I.; Friedrich,S. K.; Grubbs, R. H.; Bansleben, D. A. Science 2000, 287, 460-462.Additional catalysts are disclosed in Ittel, S. D.; Johnson, L. K.;Brookhart, M. Chem. Rev. 2000, 100, 1169-1203 and Boffa, L. S.; Novak,B. M. Chem. Rev. 2000, 100, 1479-1493. Moody, L. S.; MacKenzie, P. B.;Killian, C. M.; Lavoie, G. G.; Ponasik, J. A.; Barrett, A. G. M.; Smith,T. W.; Pearson, J. C. WO 0050470 discloses improvements or variations oflargely existing ligands and some new ligands on late metal catalysts,e.g., ligands derived from pyrrole amines instead of anilines and alsoligands based on anilines with 2,6-ortho substituents where these orthosubstituents are both aryl groups or any aromatic group. Specificexamples would be alpha-diimine-based nickel catalysts andsalicylaldimine-based nickel catalysts derived from the pyrrole aminesand ortho-aromatic-substituted anilines. Some of these derivatives showimproved lifetimes/activities/productivities/hydrogen response/potentialfunctional group tolerance, etc. Another useful catalyst is a functionalgroup tolerant, late metal catalyst usually based on Ni(II) or Pd(II).Useful catalysts are disclosed in WO 98/56837 and U.S. Pat. No.5,677,405.

[0053] Any suitable polymerization conditions may be employed in theprocess of making the polymer. Typically, when metal catalyzed vinyladdition polymerization is used the temperatures are held below about80° C., typically between 20° C. and 80° C. Suitable known solvents maybe used such as trichlorobenzene or p-xylene.

[0054] It is desirable that binder polymers used in photoresistcompositions be highly transparent at the wavelength of light used forcreating the photoimage. Preferably, the binder has an absorptioncoefficient of less than 4.0 μm⁻¹, more preferably of less than 3.5μm⁻¹, and, still more preferably, of less than 2.5 μm⁻¹ at thewavelength. As shown in an example, binder polymers having thefluorinated cyclic ether grouping can have a high degree of transparencyat 157 nm making these compositions especially useful at thiswavelength.

[0055] Some illustrative, but nonlimiting, examples of comonomerscontaining a fluorinated cyclic ether group within the scope of thisinvention are presented below:

[0056] The fluorine-containing binder polymer of this invention may,optionally comprise additional protected fluoroalcohol functionalgroups. Some illustrative, but not limiting examples of representativecomonomers containing protected fluoroalcohol groups are describedbelow:

 CH₂═CHO(CH₂)₂OCH₂C(CF₃)₂OCH₂OCH₃

[0057] The fluorine-containing polymer may be photactive, i.e. thephotoactive component may be chemically bonded to thefluorine-containing polymer. This may be accomplished by chemicallybonding the photoactive component to a monomer which then undergoescopolymerization to the monomers, thus eliminating the need for aseparate photoactive component.

[0058] A fluorine-containing polymer of this invention may comprise arepeat unit derived from at least one ethylenically unsaturated compoundcharacterized in that at least one ethylenically unsaturated compound ispolycyclic and at least one ethylenically unsaturated compound containsat least one fluorine atom covalently attached to an ethylenicallyunsaturated carbon atom.

[0059] One or more additional monomers may be used in the preparation ofthe fluorine-containing polymers. In general, it is contemplated that anacrylate monomer may be suitable as the additional monomer in preparingthe polymers. Typical additional monomers include acrylates, olefinscontaining electron-withdrawing groups (other than fluorine) directlyattached to the double bond. These terpolymers may be made byfree-radical polymerization, for example, acrylonitrile, vinyl chloride,vinylidene chloride. Vinyl acetate is also useful as an additionalmonomer.

[0060] Alternately, the fluorine-containing polymer may contain a spacergroup.

[0061] The spacer group is a hydrocarbon compound containing vinylicunsaturation and optionally, containing at least one heteroatom, such asan oxygen atom or a nitrogen atom. The hydrocarbon compound contemplatedas the spacer group contains, typically, 2 to 10, more typically 2 to 6carbon atoms. The hydrocarbon may be straight chain or branched chain.Specific examples of suitable spacer groups are selected from the groupconsisting of ethylene, alpha-olefins, 1,1′-disubstituted olefins, vinylalcohols, vinyl ethers, and 1,3-dienes. Typically, when the spacer groupis and alpha olefin, it is selected from the group consisting ofethylene, propylene, 1-butene, 1-pentene, 1-hexene and 1-octene.Typically, when the spacer group is a vinyl ether it is selected fromthe group consisting of methyl vinyl ether and ethyl vinyl ether.Typically vinyl alcohols would be obtained by post-polymerizationhydrolysis of a functional group already incorporated into the polymerbackbone, e.g. the acetate group of vinyl acetate. Typically when thespacer group is a 1,3-diene it is butadiene. Typically when the spacergroup is a 1,1′-disubstituted olefin it is isobutylene or isopentene.

[0062] The ratio of spacer group containing monomer and other monomerscan be important. Typical ranges for each are about 30% to about 70%.Alternately, spacer groups selected from the group consisting ofethylene, alpha-olefins, 1,1′-disubstituted olefins, vinyl alcohols,vinyl ethers, and 1,3-dienes may be present in the polymer. Otherpolymer types such as methacrylates and acrylates may also be used.

[0063] The quantity of polymeric binder in the photoresist compositionmay be in the amount of about 50 to about 99.5 weight % based on thetotal weight of the photoresist composition (solids).

Photoactive Component (PAC)

[0064] The photoresist composition contains a combination of binder andphotoactive component.

[0065] If the polymer of the binder itself is photoactive, a separatephotoactive component is not required. It is contemplated that thephotoactive component may be chemically bonded to the polymer of thebinder. A system in which the polymeric binder itself is photochemicallyactive is described in EP 473547. Therein a photoresist comprises anolefinically unsaturated sulfonium or iodonium salt (the photochemicallyactive component) copolymerized with an olefinically unsaturatedcomonomer containing an acid sensitive group yielding aradiation-sensitive copolymer that would be an effective photoactivepolymeric binder.

[0066] When the compositions of this invention contain a separatephotoactive component (PAC) the binder itself is usually not photactive.

[0067] The photoactive component (PAC) usually is a compound thatproduces either acid or base upon exposure to actinic radiation. If anacid is produced upon exposure to actinic radiation, the PAC is termed aphotoacid generator (PAG). If a base is produced upon exposure toactinic radiation, the PAC is termed a photobase generator (PBG).

[0068] Suitable photoacid generators for this invention include, but arenot limited to, 1) sulfonium salts (structure A), 2) iodonium salts(structure B), and 3) hydroxamic acid esters, such as structure C.

[0069] In structures IV-V, R₁-R₃ are independently substituted orunsubstituted aryl or substituted or unsubstituted C₁-C₂₀ alkylaryl(aralkyl). Representative aryl groups include, but are not limited to,phenyl and naphthyl. Suitable substituents include, but are not limitedto, hydroxyl (—OH) and C₁-C₂₀ alkyloxy (e.g., C₁₀H₂₁O). The anion X− instructures IV-V can be, but is not limited to,SbF₆-(hexafluoroantimonate), CF₃SO₃-(trifluoromethyisuifonate═trifate),and C₄F₉SO₃-(perfluorobutylsulfonate).

Dissolution Inhibitor

[0070] When the protected material of this invention is a dissolutioninhibitor, it includes compounds which have been found to have asufficiently low absorption coefficient for use in microlithography atthe imaging wavelengths. Specifically, the compounds of this inventionmay have an absorption coefficient of less than about 4.0 μm⁻¹ at awavelength of 157 nm, typically, less than about 3.5 μm⁻¹ at awavelength of 157 nm, and still more typically less than about 3.0 μm⁻¹at a wavelength of 157 nm and still more typically less than about 2.5μm⁻¹ at a wavelength of 157 nm. Dissolution inhibitors may satisfymultiple functional needs including dissolution inhibition, plasma etchresistance, plasticising and adhesion behavior of resist compositions.

[0071] The protected material may be a dissolution inhibitor. Thedissolution inhibitor usually comprises a paraffinic or cycloparaffinicor oligomeric compound. The dissolution inhibitor may have a structurecomprising the same monomer components as the binder but usually it hasa lower molecular weight than the polymer of the binder. For example,the dissolution inhibitor may contain a at least one functional grouphaving the structure:

—C(R_(f))(R_(f)′)OR₃

[0072] as described above. The dissolution inhibitor may also comprise acyclic ester that can be opened by photogenerated acid in the absence ofmoisture.

[0073] However, when the protected material is a dissolution inhibitor,the polymeric binder may be any polymer which has the transparencyproperties suitable for use in microlithography. It is contemplated thatbinders suitable for the present invention may include those polymerswhich are typically incorporated into chemically amplified 248 (deep UV)and 193 nm photoresists for imaging at longer wavelengths. A typical 248nm resist binder is based on polymers of para-hydroxystyrene. Otherexamples of suitable 248 nm resist binders can be found in the referenceIntroduction to Microlithography, Second Edition by L. F. Thompson, C.G. Willson, and M. J. Bowden, American Chemical Society, Washington, DC,1994, chapter 3. Binders useful for 193 nm photoresists includecycloolefin-maleic anhydride alternating copolymers [such as thosedisclosed in F. M. Houlihan et al., Macromolecules, 30, pages 6517-6534(1997); T. Wallow et al., Proc. SPIE, 2724, 355; and F. M. Houlihan etal., Journal of Photopolymer Science and Technology, 10, 511(1997)],polymers of functionalized norbornene-type monomers prepared bymetal-catalyzed vinyl addition polymerization or ring-opening metathesispolymerization [such as those disclosed in U. Okoroanyanwu et al. J. MoLCat. A: Chemical 133, 93 (1998), and PCT WO 97/33198], and acrylatecopolymers [those described in U.S. Pat. No. 5,372,912]. Photoresistbinders that are suitable for use with this invention also include thosewhich are transparent at wavelengths below 248 and 193 nm such as thosepolymers containing fluoroalcohol functional groups [such as thosedisclosed in K. J. Pryzbilla et al. Proc. SPIE 1672, 9 (1992), and H.Ito et al. Polymn. Mater. Sci. Eng. 77, 449 (1997)].

[0074] Typical examples of polymers which are also useful as adissolution inhibitor are those which have been developed for use inchemically amplified photoresists which are imaged at an irradiationwavelength of 157 nm. Specific examples of such polymers arefluoropolymers and fluoropolymers containing fluoroalcohol functionalgroups. Suitable examples have been disclosed in WO 00/17712, WO00/25178 and PCT/US00/11539 filed Apr. 28, 2000, with the proviso thatthe photoresist composition in its unexposed state does not have acidgroups with a pKa of <11, typically <12, and more typically <14 when theprotecting group is a cyclic ether represented by Structures I and II.

[0075] Dissolution inhibitors having the protecting groups of thisinvention may comprise a paraffinic or cycloparaffinic compoundcontaining at least one protecting group, typically at least two, moretypically 2 to about 10 and most typically 2 to 3 cyclic etherprotecting groups having structure I, II or III as described above.

[0076] Typically, when the compound contains at least 2 of theprotecting groups there is improved solubility of the dissolutioninhibitor in the developed form and less solubility in the undevelopedform.

[0077] Typically, R_(f) and R_(f)′ are independently a perfluoroalkylgroup of 1 to about 5 carbon atoms, more typically a perfluoroalkylgroup of 1 to about 3 carbon atoms, and most typically R_(f) and R_(f)′are both trifluoromethyl (CF₃).

[0078] The fluoroalkyl groups, designated as R_(f) and R_(f)′, can bepartially fluorinated alkyl groups or fully fluorinated alkyl groups(i.e., perfluoroalkyl groups), as described above.

[0079] In preferred cases according to the invention, there will besufficient fluorine substitution present in the fluorinated alkyl groupsof the fluoroalcohol functional group such that the hydroxyl group willhave a pKa value as follows: 5<pKa<11.

[0080] In one aspect, the dissolution inhibitor is an oligomercomprising a repeat unit derived from at least one ethylenicallyunsaturated compound containing a protected fluoroalcohol functionalgroup having one or more A cyclic ether group or B cyclic ester group,the structures of which are described above.

[0081] An oligomer is a low molecular weight polymer (e.g. dimer,trimer, tetramer), in the present case, with a number average molecularweight of less than or equal to 3000. As is well known to those skilledin the art, certain ethylenically unsaturated compounds (monomers)undergo free radical polymerization or metal-catalyzed additionpolymerization to form polymers having repeat unit(s) derived from theethylenically unsaturated compounds. By suitable adjustments inpolymerization conditions and especially by employing a chain transferagent or chain terminating agent in the synthesis, the molecular weightof the product may be controlled to the desired range. Chain transferagents which are useful for controlling molecular weight in free radicalpolymerizations are well known in the art and include prirriary andseconday alcohols; such as methanol, ethanol and 2-propanol,chlorocarbons, such as carbon tetrachloride, and thiols, such as dodecylmercaptan. Transition metal-catalyzed addition polymerization ofmonomers containing cyclic fluorinated ether groups may be employed.Molecular weight can be reduced so as to form oligomers by the additionof suitable chain-transfer agents; for example, hydrogen, silanes, orolefins such as ethylene, propylene, or 1-hexene. The use of olefins tocontrol and reduce molecular weight in polymerizations ofnorbornene-type monomers catalyzed by nickel and palladium catalysts isknown in the art; for example, see U.S. Pat. No. 5,741,869; U.S. Pat.No. 5,571,881; U.S. Pat. No. 5,569,730 and U.S. Pat. No. 5,468,819.

[0082] Some illustrative, but nonlimiting, examples of representativemonomers containing a fluorinated ether functional group and within thescope of the invention are presented below:

[0083] In another aspect of this invention, the dissolution inhibitor isa compound comprising the following structures:

[0084] wherein A is a paraffinic or cycloparaffinic group containing 2to 30 carbon atoms, R_(f) and R_(f)′ are as described hereinabove b isan integer ranging from at least 1, typically at least 2, more typically2 to about 10 and most typically 2 to 3.

[0085] The paraffinic or cycloparaffinic group is understood to be onecomprising carbon and hydrogen atoms and to be substantially free ofethylenic, acetylenic or aromatic unsaturation. The paraffinic orcycloparaffinic group may contain heteroatoms selected from the groupconsisting of fluorine, chlorine and oxgen. Such heteroatoms may formsubstituent groups which do not substantially contribute to absorptionat short wavelengths of light. Specific examples of such oxygencontaining substituent groups are hydroxyl and ether. For example, acycloparaffinic starting material is 4,4′-isopropylidenedicyclohexanol.Some illustrative, but nonlimiting, examples of dissolution inhibitorswithin the scope of this embodiment are presented below:

[0086] In cases wherein the dissolution inhibitor of this inventioncontains more than one fluorinated cyclic ether group, the R_(f) andR_(f)′ groups may be the same or different.

[0087] The fluorinated ether group may be used alone or it can be usedin combination with one or more other protected acid groups, such asprotected fluoroalcohol or carboxylic acid groups.

[0088] The dissolution inhibitor may be prepared by processes know inthe art, for example, the materials shown above containing thebis(trifluoromethyl)oxetane groups may be made by reaction ofcorresponding bisvinyl ethers with hexafluoroacetone as disclosed inU.S. Pat. No. 3,164,610 (1964) or in Izv. Akad. Nauk Ser. Khim. 1967,pp. 918-921.

[0089] Some dissolution inhibiting compounds also serve as plasticizersin resist compositions.

[0090] A dissolution inhibiting amount of the dissolution inhibitor iscombined with a binder and any other photoresist additives. Thedissolution inhibitor may be present in the amount of about 0.5 to about50 weight %, more typically about 1 to about 35 weight %, and mosttypically about 5 to about 20 weight %, based on the total weight of thephotoresist composition (solids).

Other Components

[0091] The compositions of this invention can contain optionaladditional components. Examples of such additional components include,but are not limited to, resolution enhancers, adhesion promoters,residue reducers, coating aids, plasticizers, and T_(g) (glasstransition temperature) modifiers.

Process Steps

[0092] Imagewise Exposure

[0093] The photoresist compositions of this invention are sensitive inthe ultraviolet region of the electromagnetic spectrum and especially tothose wavelengths ≦365 nm. Imagewise exposure of the resist compositionsof this invention can be done at many different UV wavelengthsincluding, but not limited to, 365 nm, 248 nm, 193 nm, 157 nm, and lowerwavelengths. Imagewise exposure is preferably done with ultravioletlight of 248 nm, 193 nm, 157 nm, or lower wavelengths, preferably it isdone with ultraviolet light of 193 nm, 157 nm, or lower wavelengths, andmost preferably, it is done with ultraviolet light of 157 nm or lowerwavelengths. Imagewise exposure can either be done digitally with alaser or equivalent device or non-digitally with use of a photomask.Digital imaging with a laser is preferred. Suitable laser devices fordigital imaging of the compositions of this invention include, but arenot limited to, an argon-fluorine excimer laser with UV output at 193nm, a krypton-fluorine excimer laser with UV output at 248 nm, and afluorine (F2) laser with output at 157 nm. Since, as discussed supra,use of UV light of lower wavelength for imagewise exposure correspondsto higher resolution (lower resolution limit), the use of a lowerwavelength (e.g., 193 nm or 157 m or lower) is generally preferred overuse of a higher wavelength (e.g., 248 nm or higher).

[0094] Development

[0095] The polymers in the resist compositions of this invention mustcontain sufficient functionality for development following imagewiseexposure to UV light. Typically, the functionality is acid or protectedacid such that aqueous development is possible using a basic developersuch as sodium hydroxide solution, potassium hydroxide solution, orammonium hydroxide solution. The protecting groups of the presentinvention are advantageous since they do not require moisture todeprotect the developable group, in addition to not yielding a volatiledeprotection product due to the cyclic nature of the protecting group.

[0096] When an aqueous processable photoresist is coated or otherwiseapplied to a substrate and imagewise exposed to UV light, development ofthe photoresist composition may require that the binder material. shouldcontain sufficient protected acid groups that are at least partiallydeprotected upon exposure to render the photoresist (or otherphotoimageable coating composition) processable in aqueous alkalinedeveloper. In case of a positive-working photoresist layer, thephotoresist layer will be removed during development in portions whichare exposed to UV radiation but will be substantially unaffected inunexposed portions during development by aqueous alkaline liquids suchas wholly aqueous solutions containing 0.262 N tetramethylammoniumhydroxide (with development at 25° C. usually for less than or equal to120 seconds). In case of a negative-working photoresist layer, thephotoresist layer will be removed during development in portions whichare unexposed to UV radiation but will be substantially unaffected inexposed portions during development using either a critical fluid or anorganic solvent.

[0097] A critical fluid, as used herein, is one or more substancesheated to a temperature near or above its critical temperature andcompressed to a pressure near or above its critical pressure. Criticalfluids in this invention are at least at a temperature that is higherthan 15° C. below the critical temperature of the fluid and are at leastat a pressure higher than 5 atmospheres below the critical pressure ofthe fluid. Carbon dioxide may be used for the critical fluid in thepresent invention.

[0098] Various organic solvents can also be used as developer in thisinvention. These include, but are not limited to, halogenated solventsand non-halogenated solvents. Halogenated solvents are preferred andfluorinated solvents are more preferred.

Substrate

[0099] The substrate employed in this invention can illustratively besilicon, silicon oxide, silicon nitride, or various other materials usedin semiconductive manufacture.

EXAMPLES Example 1

[0100] A compound having the following structure was prepared using thefollowing procedure:

[0101] 25 g of vinyl ether prepared from exo-5-norbornen-2-ol weredissolved in 100 mL of ether, 0.5 g of potassium carbonate was added toa solution and 32 g of hexafluoroacetone (5% excess) fed into reactionvessel as a gas at 10-15° C. The reaction mixture was brought to 25° C.and was agitated at this temperature for 1 h. The solvent was removedunder vacuum at 30° C. and the crude product was distilled under vacuumto give 34.8 g (63%) of product >95% purity, b.p. 50-52° C./0.38 mm Hg.¹H NMR (CDCl₃): 1.3-1.8 (4H), 2.7-3.1 (4H), 3.8 (2H), 5.6 (1H), 5.8 (1H)6.1 (1H) ppm, ¹⁹F NMR (CDCl₃): −79.13 (3F, m), −79.28 (3F, m)PPM.

Example 2

[0102] Oxetane A monomer having the following structure was preparedusing the following procedure:

[0103] 22.8 g (0.2 mol) of CH₂═CHO(CH₂)₂OCH═CH₂ were dissolved in 100 mLof dry ether, and 33 g (0.2 mol) of hexafluoroacetone were introducedinto reactor as a gas at −20° C. The reaction mixture was maintained at−15° C. for 30 min, warmed up to 25° C., solvent was removed undervacuum and residue (55 g) was distilled under reduced pressure in thepresence of 0.1 g of K₂CO₃ to give 26 g (46.6%) of fraction b.p. 43-48°C./0.25 mm Hg (major fraction 45-46° C.), which was found to be thetitle compound of >98% purity. The residue 25 g based on NMR data wasmostly the product of condensation of one mole of divinyl ether with twomoles of hexafluoroacetone.

[0104]¹H NMR (acetone-d₆): 2.60(1H), 2.8 (1H, dd), 3.15 (1H, dd),3.6-4.2(5H), 5.65 (1H,t), 6.35 (1H, dd) PPM; ¹⁹F NMR (acetone-d₆):−79.72 (3F, m), −79.83(3F, m) PPM.

Example 3

[0105] A Bis(trifluorooxetane)-containing polymer was synthesized usingthe following procedure:

[0106] A 200 mL stainless steel autoclave was charged with 15.4 g (0.08mol) of adamantanemethylvinyl ether (AdVether), 22.4 g (0.08 mol) of theoxetane monomer of Example 2 (OXVE), 50 mL of tert-butanol, 25 mL ofisopropanol, 0.5 g of potassium carbonate and 0.4 g of Vazo® 52. Thevessel was closed, cooled, evacuated and purged with nitrogen severaltimes. It was then charged with 24.0 g (0.24 mol) of tetrafluoroethylene(TFE). The autoclave was agitated with the vessel contents at 50° C. forabout 18 hr resulting in a pressure change from 294 psi to 134 psi. Thevessel was cooled to room temperature and vented to one atmosphere. Thevessel contents were removed using acetone to rinse giving a clearslightly yellow solution. This solution was added slowly to excess icewater resulting in precipitation of a white polymer which was driedovernight in a vacuum oven. The yield was 49.8 g (81%). GPC analysis:Mn=35,500; Mw=73300; Mw/Mn=2.06. DSC analysis: A Tg of 35° C. wasobserved on second heat. ¹H NMR (δ, THF-d8) 1.48-2.05 (m, 15 H fromadamantane rings), 2.37-2.80 (m, CH₂ from polymer backbone), 2.91 (m, 1oxetane ring H), 3.15 (m, 1 oxetane ring H), 3.20-3.40 (m, CH₂O attachedto adamantane ring), 3.87 (m, OCH₂CH₂O attached to oxetane ring), 4.22and 4.40 (m, CH on polymer backbone), 5.68 (m, acetal hydrogen). Byintegration, the ratio of OXVE to AdVether in the polymer is 57:43. ¹⁹FNMR (δ, THF-d8) −78.9 (CF₃), −107 to −125 (CF₂). From the fluorine NMR,the ratio of OXVE to TFE in the polymer is 33 to 67. Combining theseratios suggests an overall composition of 53% TFE, 20% AdVether and 26%OXVE.

[0107] Anal. Found: C, 46.34; H, 4.43; F, 37.96.

Example 4

[0108] A Bis(trifluoromethyl)oxetane-containing polymer was preparedusing the following procedure:

[0109] A 200 mL stainless steel autoclave was charged with 16.0 g (0.17mol) of norbornene, 21.1 g (0.07 mol) of the oxetane-containing monomerof Example 1 (NB-OX), 75 mL of 1,1,2-trichlorotrifluoroethane, 0.5 g ofpotassium carbonate and 1.0 g of Perkadox® 16. The vessel was closed,cooled, evacuated and purged with nitrogen several times. It was thencharged with 30 g (0.30 mol) of tetrafluoroethylene (TFE). The autoclavewas agitated with the vessel contents at 50° C. for about 18 hrresulting in a pressure change from 228 psi to 201 psi. The vessel wascooled to room temperature and vented to one atmosphere. The vesselcontents were removed using 1,1,2-trichlorotrifluoroethane to rinsegiving a clear solution. This solution was added slowly to excessmethanol resulting in precipitation of a white polymer which was driedover night in a vacuum oven. Yield was 17.1 g (25%). GPC analysis:Mn=5200; Mw=8200; Mw/Mn=1.57. DSC analysis: A Tg of 111° C. was observedon second heat. The fluorine NMR spectrum showed peaks at −76.8 to −78.6ppm (CF₃) and −95 to −125 ppm (CF₂) confirming incorporation of NB-OXand TFE, respectively, in a ratio of 1:2.8. A thin film of the polymerobtained by spin coating from a 2-heptanone solution showed anabsorbance of 1.33 μm⁻¹ at 157 nm, indicating a high degree of opticaltransparency at this wavelength.

[0110] Analysis found: C, 52.03; H, 4.79; F, 37.22.

Example 5

[0111] The oxetane containing polymer was isomerized using the followingprocedure:

[0112] 6 g of TFE/AdVether/OXVE terpolymer prepared in Example 3, weredissolved in 80 mL of ether and 0.1 g of 96% H₂SO₄ was added dropwiseover a period of 5 min, to keep temperature of reaction mixture <25° C.and reaction mixture was agitated at ambient temperature for 1 h.Slightly yellow solution was filtered through glass wool. Based on NMRthe solution at this point did not contain any material containingoxetane ring. ¹H NMR spectrum of the material exhibit two dublets at 4.9and 7.1 PPM, typical of vinyl protons of CH═CH fragment (1H NMR ofstarting material contained only one signal in this region −6 PPM); ¹⁹Fspectrum contained only one signal at −79.0 PPM (two signals −79.01 and−79.2 PPM in starting material). Solvent was removed under vacuum toleave 5.2 g of slightly yellow polymer, which was not soluble in ether,acetone and ethyl acetate. 4.5 g of this material was dissolved in 30 mLof dimethylacetamide at 60-70° C. (4h) and the solution was left atambient temperature for 2 days. Precipitate formed was separated fromliquid, washed with H₂O, filtered, washed with methanol and air-dry for1 hr. at 25° C. 4 g of white polymer were isolated. In IR spectrum ofthis material (KBr) were found two new bands at 1633 (C═C) and 3433(OH), which were not present in IR spectrum of starting material.

Example 6 Preparation of Gamma,Gamma-dimethyl-alpha-methylene-gamma-butyrolactone (g,g-DimethylMBL, orDM-MBL) Example 6a Preparation of Triisopropylbenzenesulfonyl Hydrazide

[0113]

[0114] A 500 mL, three neck flask with a mechanical stirrer,thermometer, addition funnel, and a condenser with nitrogen tee wascharged with 2,4,6-triisopropylbenzenesulfonyl chloride (100 g, 0.33mol) and THF (120 mL) and cooled to 10° C. Hydrazine monohydrate (36 g,0.73 mol) was added dropwise via addition funnel over 20 minutes(exothermic) while maintaining the temperature at 10-15° C. The reactionbecame a yellow slurry, then a cloudy solution, then a yellow slurry. Atthe end of the addition, a precipitate formed. Another 80 mL THF wereadded and the solids dissolved to give a yellow solution. The mixturewas stirred for 30 min. Two layers were visible. The organic layer (toplayer) was washed with 100 mL sat'd NaCl, dried over MgSO4, filtered,and concentrated on the rotary evaporator to obtain a light yellowsolid. The solid was triturated with petroleum ether, filtered, andwashed with 300 mL petroleum ether. The solid was dried overnight undera nitrogen stream to obtain the desired product (88 g theory 98.7 g) asa white solid. Another 4 g of the desired product were obtained byconcentration of the filtrate and triturating with petroleum ether. ¹HNMR (500 MHz, CDCl3) δ 1.2 (s, 18H), 3.0 (m, 1H), 3.5 (br s, 2H), 4.0(m, 2H), 5.5 (br s, 1H), 7.3 (d, 2H); 13C NMR (125 MHz, CDCl3) δ 23.30,24.68, 29.50, 34.02, 123.82, 128.50, 151.64, 153.63.

Example 6b Preparation of Acetone 2,4,6-TriisopropylbenzenesulfonylHydrazide

[0115]

[0116] A 500 mL, 3 neck flask equipped with a mechanical stirrer,thermometer, addition funnel, and a condenser with nitrogen tee wascharged with 300 mL acetone and add 2,4,6-triisopropylbenzenesulfonylhydrazine (87.9 g, 0.29 mol) with stirring. Caution: the temperaturerises from 20° C. to 30° C. upon addition of the solid. Concentrated HCl(1 mL) was added and the cloudy solution was stirred for 1 hour. Thedesired product, (solid) precipitates over the course of the reaction.The mixture was filtered and the solids washed with water (2×200 mL),and dried with a nitrogen sweep to obtain 30.7 g of the desired product.The filtrate was slowly poured in to 300 mL water with cooling to give awhite slurry. The slurry was stirred for 15 minutes, filtered, washedwith 250 mL water, and dried under a nitrogen stream to obtain 64.2 g ofthe desired product as a white solid. Combined yield: 64.2 g+30.7 g=94.9g (96%). 1H NMR (500 MHz, CDCl3) δ 1.75 (s, 18H), 1.9 (s, 3H), 1.95 (s,3H), 2.5 (m, 1H), 4.1 (m, 2H), 7.2 (s, 2H); 13C NMR (125 MHz, CDCl3) δ16.37, 23.46, 24.70, 24.84, 25.25, 29.83, 34.05, 123.68, 131.42, 151.29,153.00, 154.06.

Example 6c Preparation of g,g-Dimethyl-MBL (DM-MBL)

[0117]

[0118] A 2000 mL, 3 neck flask equipped with a mechanical stirrer,thermometer, addition funnel, and a condenser with nitrogen tee wascharged with 250 mL dimethoxyethane, acetone2,4,6-triisopropyltosylhydrazone (45 g, 0.133 mol), and cooled to −78°C. in a dry ice/acetone bath. To this was added 2.4 equivalents ofn-butyl lithium in hexanes (20.4 g, 0.32 mol. 128 mL) via additionfunnel under nitrogen. The reaction changed from clear to orange toyellow/orange. The temperature was allowed to rise to −50° C. over 10minutes. To this was added acetone (13.7 g, 0.236 mol. 1.77 equivalents)dropwise via syringe while maintaining −50° C. temperature (exothermicreaction with acetone). The reaction turns from orange/yellow to almostclear upon acetone addition. The reaction was cooled to −78° C., thenanother 1.8 equivalents n-butyl lithium (15.3 g, 0.24 mol, 96 mL) wereadded dropwise. The reaction turned from almost clear to yellow/orangeto red/orange and was allowed to stir at −78° C. for 8 minutes thenallowed to warm to −5° C. over 45 minutes. It was then held for one hourat −5° C., and then cooled back to −78° C. (dry ice/acetone) andquenched by bubbling in CO2 gas 10 min (slow, even bubbling, caution,exothermic reaction). The reaction was allowed to warm to roomtemperature and quenched with 400 mL cold water (CAUTION, add dropwise).To the mixture was added 200 mL EtOAc and the reaction was filteredthrough a bed of celite and celite washed with 200 mL EtOAc. The layerswere separated and the aqueous layer acidified with trifluoroacetic acid(74 g) to pH=1 and stirred overnight. A small amount of solidsprecipitated over that time. The aqueous layer was extracted with EtOAc,(3×100 mL) and the combinedorganic layers were washed. with 100 mL sat'dNaCl, dried over MgSO4, and concentrated in vacuo to give 90 g of acrude yellow oil This oil was purified by column chromatography: silicagel, 1/4 EtOAc/Hexanes (Rf 0.4) to obtain 15.4 g (92%) of the desiredproduct as a pale orange oil (87% pure by GC). The product was furtherpurified by vacuum distillation to obtain the desired product as acolorless liquid; BP 50-53° C./0.4 mm

[0119] Hg; ¹H NMR (500 MHz, CDCl3) δ 1.35 (s, 6H), 2.7 (m, 2H), 5.55 (m,1H), 6.15 (m, 1H); 13C NMR (125 MHz, CDCl3) 628.63, 41.43, 82.26,122.62, 136.32, 170.46; (97.8% by GC).

Example 7

[0120] The methylmethacrylate(MMA)Imethacrylic acid(MM)/dimethyltuliplin(DMMBL) (42.1/16.85/41.08 w/w/w) copolymer was prepared by charging thefollowing components to a 100 mL flask equipped with a thermocouple,stirrer, dropping funnel, reflux condenser and the means for bubblingnitrogen through the reaction. Parts by Weight Grams Portion 1 Methylmethacrylate (MMA) 0.8 Methacrylic acid (MAA) 0.32 Dimethyltuliplin(DMMBL) 0.78 Methylethyl ketone (MEK) 10.00 Portion 2 MEK 2.02,2′-Azobis (2,4-Dimethyl Valeronitrile): Vazo ®-52 0.08 Portion 3 MEK16.0 2,2′-Azobis (2,4-Dimethyl Valeronitrile): Vazo ®-52 0.96 Portion 4Methyl methacrylate (MMA) 7.20 Methacrylic acid (MAA) 2.88Dimethyltuliplin (DMMBL) 7.03 Total 48.05

[0121] The monomers in portion 1 were dissolved in 10 grams of MEK inthe reaction flask. Nitrogen was sparged through the solution in thereaction flask while heating the solution by a mantle to reach thesolution temperature to reflux. Portion 2, Vazo®-52 was dissolved in 2grams of MEK in a container and added into the reaction flask. Then thePortion 3, Vazo®-52 initiator solution and Portion 4 monomer mixturewere fed into the reaction flask at a uniform rate over 6 hours and 4hours respectively at the reflux temperature. After the initiator feedwas over, the polymerization was continued for another 1 hour at refluxtemperature. Finally the polymer was precipitated by adding the polymersolution into a large excess (500 grams) of petroleum ether andfiltered. The polymer was rinsed twice with a small amount of petroleumether, filtered and dried in a vacuum oven overnight at 25-30° C. Thepolymer yield was 13.58 grams (71.5%).

Example 8

[0122] The following solution was prepared and magnetically stirredovernight. Component Wt. (gm) MMA/MAA/DM-MBL copolymer 1.149 (weightfeed ratio: 42.1/16.9/41.0) as described in Example 7 Cyclohexanone7.803 t-Butyl Lithocholate 0.300 6.82% (wt) solution oftriphenylsulfonium nonaflate 0.748 dissolved in cyclohexanone which hadbeen filtered through a 0.45 μ PTFE syringe filter.

[0123] Spin coating was done using a Brewer Science Inc. Model-100CBcombination spin coater/hotplate on a 4 in. diameter Type “P”, <100>orientation, silicon wafer. Development was performed by hand dipping ina dish.

[0124] The wafer was prepared by depositing 6 mL of hexamethyldisilazane(HMDS) primer and spinning at 5000 rpm for 10 seconds. Then about 3 mLof the above solution, after filtering through a 0.45 μm PTFE syringefilter, were deposited and spun at 3000 rpm for 60 seconds, and baked at120° C. for 60 seconds.

[0125] 248 nm imaging was accomplished by exposing the coated wafer tolight obtained by passing broadband UV light from an ORIEL Model-82421Solar Simulator (1000 watt) through a 248 nm interference filter whichpasses about 30% of the energy at 248 nm. Exposure time was 30 seconds,providing an unattenuated dose of 20.5 mJ/cm². By using a mask with 18positions of varying neutral optical density, a wide variety of exposuredoses were generated. After exposure the exposed wafer was baked at 120°C. for 120 seconds.

[0126] The wafer was developed in aqueous tetramethylammonium hydroxide(TMAH) solution (OHKA NMD-3, 1.19% TMAH solution) for 30 sec to give apositive image.

What is claimed is:
 1. A photoresist composition comprising: (a) aprotected material comprising a protecting group which is: A. a cyclicether group having the structure I or II:

 wherein R_(f) and R_(f)′ are the same or different fluoroalkyl groupsof from one to about ten carbon atoms or taken together are (CF₂)_(a)wherein a is an integer ranging from 2 to about 10, R independentlyrepresents a hydrogen atom or a straight chain or branched chain alkylgroup of 1 to about 10 carbon atoms, and p is an integer of from 0 toabout 8; wherein the protected material is substantially free of an acidgroup with a pKa of <11; and B. a cyclic ester having structure III:

 wherein R₁ and R₂ independently represent a substituted or anunsubstituted straight chain or branched chain alkyl group, aromaticgroup, aralkyl, or alkaryl group, n is an integer of 1 to about 4; and(b) a photoactive component.
 2. The photoresist composition of claim 1wherein the cyclic ether protecting group has the structure:

wherein R_(f) and R_(f)′ are the same or different fluoroalkyl groups offrom one to about ten carbon atoms or taken together are (CF₂)_(a)wherein a is an integer ranging from 2 to about 10, R independentlyrepresents a hydrogen atom or a straight chain or branched chain alkylgroup of 1 to about 10 carbon atoms, and p is an integer of from 0 toabout
 8. 3. The photoresist composition of claim 2 wherein R_(f) andR_(f)′ are each perfluoroalkyl groups of 1 to 5 carbon atoms, p is zeroand R is a hydrogen atom.
 4. The photoresist composition of claim 3wherein R_(f) and R_(f)′ are each CF₃.
 5. The photoresist composition ofclaim 1 wherein in the cyclic ester group B, n is 1 and R₁ and R₂ areeach CH₃, and at least one point of attachment to the protected materialis through a saturated ring carbon, R₁ or R₂.
 6. The photoresistcomposition of claim 1 wherein the protected material is a polymericbinder.
 7. The photoresist composition of claim 6 wherein the polymericbinder has an absorption coefficient of less than about 4.0 μm⁻¹ at awavelength of about 157 nm.
 8. The photoresist composition of claim 6wherein the cyclic ester group B is incorporated by copolymerizationwith γ, γ-dimethyl-α-methylene-γ-butyrolactone.
 9. The photoresistcomposition of claim 1 wherein the protected material is a dissolutioninhibitor.
 10. The photoresist composition of claim 9 wherein thedissolution inhibitor comprises a paraffinic, cycloparaffinic oroligomeric compound containing at least one cyclic ether protectinggroup A of structures I or II

wherein R_(f) and R_(f)′ independently represent fluoroalkyl groups offrom one to about ten carbon atoms or taken together are (CF₂)_(a)wherein a is an integer ranging from 2 to about 10, R independentlyrepresents a hydrogen atom or a straight chain or branched chain alkylgroup of 1 to about 10 carbon atoms, and p is an integer of from 0 toabout 8; wherein the protected material is substantially free of an acidgroup with a pKa of <11.
 11. The photoresist composition of claim 9wherein the dissolution inhibitor comprises a paraffinic,cycloparaffinic or oligomeric compound containing at least one cyclicester protecting group of the structure III

wherein R₁ and R₂ independently represent an unsubstituted straightchain or branched chain alkyl group having 1 to 10 carbon atoms;aromatic, aralkyl, or alkaryl group having 6 to 14 carbon atoms; orsubstituted groups thereof containing at least one O, S, N, P orhalogen; n is an integer ranging from 1 to about
 4. 12. The photoresistcomposition of claim 9 wherein the dissolution inhibitor has anabsorption of less than about 4.0 μm⁻¹ at a wavelength of about 157 nm.13. A process for preparing a photoresist image on a substratecomprising, in order: (W) forming a photoresist layer on a substrate,wherein the photoresist layer is prepared from a photoresist compositioncomprises: (a) a protected material comprising a protecting group whichis: A. a cyclic ether group having structure I or II:

 wherein R_(f) and R_(f)′ are the same or different fluoroalkyl groupsof from one to about ten carbon atoms or taken together are (CF₂)_(a)wherein a is an integer ranging from 2 to about 10, R independentlyrepresents a hydrogen atom or a straight chain or branched chain alkylgroup of 1 to about 10 carbon atoms, and p is an integer of from 0 toabout 8; wherein the protected material is substantially free of an acidgroup with a pKa of <11; and B. a cyclic ester having structure III:

 wherein R₁ and R₂ independently represent an unsubstituted straightchain or branched chain alkyl group having 1 to 10 carbon atoms;aromatic, aralkyl, or alkaryl group having 6 to 14 carbon atoms; orsubstituted groups thereof containing at least one O, S, N, P orhalogen; n is an integer ranging from 1 to about 4; and (b) aphotoactive component; (X) imagewise exposing the photoresist layer toform imaged and non-imaged areas; and (Z) developing the exposedphotoresist layer having imaged and non-imaged areas to form the reliefimage on the substrate.
 14. The process of claim 13 wherein theprotecting group comprises a cyclic ether group having the structure:

wherein R_(f) and R_(f)′ are the same or different fluoroalkyl groups offrom one to about ten carbon atoms or taken together are (CF₂)_(a)wherein a is an integer ranging from 2 to about 10, R independentlyrepresents a hydrogen atom or a straight chain or branched chain alkylgroup of 1 to about 10 carbon atoms, and p is an integer of from 0 toabout
 8. 15. The process of claim 13 wherein the protecting group is acyclic ester group having the structure III:

wherein R₁ and R₂ independently represent an unsubstituted straightchain or branched chain alkyl group having 1 to 10 carbon atoms;aromatic, aralkyl, or alkaryl group having 6 to 14 carbon atoms; orsubstituted groups thereof containing at least one O, S, N, P orhalogen; n is an integer ranging from 1 to about
 4. 16. The process ofclaim 13 wherein the protected material is a polymeric binder.
 17. Theprocess of claim 16 wherein the polymeric binder has an absorption ofless than about 4.0 μm⁻¹ at a wavelength of about 157 nm.
 18. Theprocess of claim 15 wherein the cyclic ester group B is derived frompolymerization with γ,γ-dimethyl-α-methylene-γ-butyrolactone.
 19. Theprocess of claim 13 wherein the protected material is a dissolutioninhibitor.
 20. The process of claim 19 wherein the dissolution inhibitorcomprises a paraffinic, cycloparaffinic or oligomeric compoundcontaining at least one cyclic ether functional groups having thestructure:

wherein R_(f) and R_(f)′ are the same or different fluoroalkyl groups offrom one to about ten carbon atoms or taken together are (CF₂)_(a)wherein a is an integer ranging from 2 to about 10, R independentlyrepresents a hydrogen atom or a straight chain or branched chain alkylgroup of 1 to about 10 carbon atoms, and p is an integer of from 0 toabout
 8. 21. The process of claim 20 wherein the protected material is adissolution inhibitor comprising a paraffinic, cycloparaffinic oroligomeric compound containing at least one cyclic ester functionalgroups having the structure:

wherein R₁ and R₂ independently represent an unsubstituted straightchain or branched chain alkyl group having 1 to 10 carbon atoms;aromatic, aralkyl, or alkaryl group having 6 to 14 carbon atoms; orsubstituted groups thereof containing at least one O, S, N, P orhalogen; n is an integer ranging from 1 to about
 4. 22. The process ofclaim 20 wherein the dissolution inhibitor has an absorption of lessthan about 4.0 μm⁻¹ at a wavelength of about 157 nm.
 23. The photoresistcomposition of claim 1 in which in structure III the at least one pointof attachment to the protected material is through a saturated ringcarbon, R₁ or R₂.
 24. The photoresist composition of claim 1 furthercomprising a solvent.
 25. The process of claim 13 in which in structureIII the at least one point of attachment to the protected material isthrough a saturated ring carbon, R₁ or R₂.
 26. A coated substrate forsemiconductor manufacture comprising a substrate having on a surfacethereof a coating of the photoresist composition of any one of claims 1to 12, 23 and
 24. 27. The coated substrate of claim 26 wherein thesubstrate comprises silicon, silicon oxide or silicon nitride.
 28. Thecoated substrate of claim 26 wherein the substrate is primed.
 29. Thecoated substrate of claim 28 wherein the substrate is primed withhexamethyldisilazane.
 30. The coated substrate of claim 26 wherein thephotoresist composition is coated onto the surface of the substrate byspin coating.